This invention is an important improvement that is suitable for use in a single log feeder which is disclosed and claimed in U.S. Pat. No. 4,624,361, granted Nov. 25, 1986, Bryant C. Hollins, assignee Exco Industries Ltd. That patent discloses and protects a basic single log feeder which is capable of sorting logs of varying diameter and feeding them one at a time to a log processing apparatus.
It has been a longstanding problem in the elongated cylinder handling industry to efficiently take a long cylindrical object from a random group of such cylindrical objects of various sizes and orientations, align the single cylindrical object in a predetermined direction and direct it to a cylinder handling apparatus. One of the industries in which this problem arises is the log handling industry. Numerous machines and processes have been designed over the years in an effort to develop an apparatus and a method of efficiently handling a wide range of straight and crooked logs of varying diameters and lengths mixed butts and ends, and aligning them one at a time in a generally parallel pattern and feeding them without interruption to a log processing machine such as a debarker or a chip and saw apparatus.
The applicant is aware of the following patents which disclose various devices for processing logs.
______________________________________ Canadian Patent No. Issue Date Inventor ______________________________________ 789,368 July 9, 1968 Ahlstedt 920,544 February 6, 1973 Lindblom 922,659 March 13, 1973 Rysti 980,820 December 30, 1975 Hartzell and Gunnerman 989,427 May 18, 1976 Valo 1,048,562 February 13, 1979 Danielsson and Ekhoim 1,114,408 December 15, 1981 Valo U. S. Pat. No. 2,751,781 June 26, 1956 McConnell 3,112,021 November, 1961 Forsberg 3,584,726 June 15, 1971 Hartzell 4,624,361 November 25, 1986 Hollins ______________________________________
Ideally, a log handling apparatus capable of handling a group of straight and crooked logs of various diameters, lengths and orientations, and single feeding them in an aligned manner to a log processing apparatus should be able to run without interruption and be capable of feeding the logs to the log processing apparatus so that the logs are virtually end to end with one another, thereby minimizing waste space between the ends of each log. In this way, a maximum number of logs are processed in a given time. However, in practice, apparatus designed for this purpose are prone to breakdown, are unduly complex, or do not carry out the job of separating the logs individually and feeding them one at a time without frequent interruptions. Thus, it is not uncommon for the apparatus to fail to make a separation between individual logs and thus, the operator must stop the machine, separate the plurality of logs and ensure that they are fed one at a time to the log processing apparatus. Interruptions of this sort are costly and labour intensive.
Of the devices disclosed and claimed in the references listed, two devices in particular are purported to be capable of selecting a log from a group of logs and feeding the log to a log processing apparatus. Canadian Pat. No. 789,368, Ahlstedt, discloses an apparatus for the selection and sidewise delivery of selected sets of long rollable objects of varying diameters from a closely spaced group of such objects, such as logs. In Ahlstedt's apparatus, a lift arm holds back the logs while in the "up" position, and releases one log while it is in the "down" position. At the same time, a second log is allowed to lodge in a pocket to hold back remaining logs. While the Ahlstedt apparatus would appear to deal adequately with logs of relatively uniform diameter, it would appear to be unreliable in dealing with logs of small diameter mixed with logs of large diameter. Lodging of a small log in the retaining pocket would increase the likelihood that a following larger diameter log would be pushed over the smaller log and hence disrupt operation.
Canadian Pat. No. 1,114,408, Valo, discloses and claims an apparatus which is designed specifically for the purpose of handling logs of varying diameter and feeding them one at a time to a log processing apparatus. However, the apparatus disclosed is relatively complex, expensive, and in practice has been found to be prone to breakdown due to its complexity. The apparatus utilizes a dual disc arrangement for separating the logs. The two discs rotate on separate shafts in opposite direction and are provided with peripheral notches which, in the extreme positions of the rotary movement of the discs, are directed substantially toward the log inlet end and the log outlet side. In practice, it has been found that the Valo apparatus cannot be operated efficiently at high speed without frequent breakdown.
The single log sorter that is disclosed and claimed in U.S. Pat. No. 4,624,361, Hollins, discloses and protects a single log feeder which is constructed of a means for receiving and holding a plurality of logs of varying diameter and length arranged parallel and abutting one another in a row, and a separate means for separating and raising the foremost log in the row from the secondarily disposed log in the row and dispensing the foremost log from the apparatus. By nature, not all logs are of the same diameter. They are also not perfectly cylindrical. The logs taper from one end to the other. Further, the logs are not necessarily straight, but are often bent or crooked, and have minor projections around the periphery of the log such as stumps of branches, and the like. As a consequence, the logs do not necessarily roll evenly and consistently down the log runway of the single log feeder. Jamming of logs occurs from time to time and as a consequence an operator must use a log pole or the like to free up the jammed logs so that they can continue to roll down the runway until they are disposed adjacent one another in parallel orientation on the runway.